Semiconductor IC chips and the packages, electronic parts, such as car-mounted power semiconductor devices, and electronic apparatuses, etc. are required to mount functions that effectively radiate the heat generated in the operation and are capable of continuously operating with high reliability. In servers and PCs, for example, CPU (Central Processing Units), which generate very much heat are used, and it is required to effectively radiate the heat generated from them to properly maintain the temperature environments inside the casings and installation sites. As the devices are more downsized and are more speeded up, the current density increases, which lead to more heat generation, and it is increasingly required to effectively radiate the heat.
Especially in a three-dimensional mounting semiconductor device having a plurality of semiconductor chips stacked, it is difficult to cool all the semiconductor chips in the stacked layers by a heat radiation device, such as a heat sink or others, provided on the chip surfaces. It is important how to effectively radiate the heat from the inside semiconductor chips.
In such background, as a proposed technique of effectively cooling the respective semiconductor chips of a three-dimensional mounting semiconductor device is noted a cooling technique using a microchannel. This technique is of providing a plurality of microchannels in a three-dimensional mounting semiconductor device and flowing a liquid for cooling in the microchannels to thereby cool the respective semiconductor chips.
The microchannel is a channel of dimensions of the micro-order for flowing a liquid. The flow of the micro-scale is a laminar flow and also generates the effect that the surface force (viscosity effect of liquid) is more influential than the body force, whereby the thermal conductivity can be improved with a low flow rate of the fluid. Thus, the heat generated from heat source can be effectively moved while required cooling efficiency can be provided. Furthermore, a merit is that the width and the height of the channel of the micro-order allows the cooling device to be downsized. Another merit is that a small use quantity of the fluid allows the degree of freedom of the design to be improved for the move area and the storage area of the fluid.
The followings are examples of related: Japanese Laid-open Patent Publication No. 05-251601; and Japanese Laid-open Patent Publication No. 06-21291.
To flow a fluid for the cooling through the microchannels provided in the three-dimensional mounting semiconductor device, it is important to ensure the joints among the plural semiconductor chips and with other members endurably to the pressure of the fluid. Especially, in the operation of the semiconductor device, often thermal expansion takes place due to heating, and the reliability of the joints is required to be improved.